I found Nutri-cal at a local feed store but I'm sure you can get it online too. She actually likes Laxatone better (kitty laxative made by the same company) and sometimes I have to give her a little lick of that to convince her she likes the Nutri-cal too!
Mimi - I tried several different scenarios to convince my skinny kitty to eat at specific feeding times, but I guess she's just more stubborn than most because nothing worked. I really think this is a cat who only eats the bare minimum to survive. She has just never been interested in eating. The looks she gives me when I try to get her to eat are really pretty funny. She looks at me like I'm totally nuts!